AuthorTopic: Antenna for 3G ‘dongle’-type USB NIC (Read 2388 times)

(1) Get a 4G router as opposed to a dongle, assuming your Firebrick has an available Ethernet interface. There are routers around that can be put into bridge mode, and in that mode they offer the WAN IP address via DHCP to the router. That way your Firebrick has direct control of the external IP.

(2) Stick with the dongle. NAT and everything, but use AA L2TP from the Firebrick to get a proper routable IP address, and IPv6. Then you can choose any 4G service based on price, service availability etc.

There is a guy on TBB forums who's in Scotland who has an external antenna, although I don't know where in Scotland. He currently has a thread asking about lightening protection as he wants to mount it on a 2 to 3 meter pole.

Surely a suitable lightning strike system offering very low resistance to earth is the way to.

There is a guy on TBB forums who's in Scotland who has an external antenna, although I don't know where in Scotland. He currently has a thread asking about lightening protection as he wants to mount it on a 2 to 3 meter pole.

IIRC from other postings, South Ayrshire. I'm sure I saw Coylton mentioned once which is a few miles inland from Ayr.

(1) Get a 4G router as opposed to a dongle, assuming your Firebrick has an available Ethernet interface. There are routers around that can be put into bridge mode, and in that mode they offer the WAN IP address via DHCP to the router. That way your Firebrick has direct control of the external IP.

Yes, I would definitely echo what aesmith said - get a proper dedicated 4G router with its own built-in Ethernet ports and WiFi.

I'm currently using a Huawei B525 with good results via Three. The B525 has 4 Ethernet ports, a USB port, plus an RJ11 port so you can connect a standard phone either to use any minutes via the SIM card, or to use a VOIP service.

(I've used Amazon for ease, but most of these items mentioned in my post can be found at different suppliers, e.g. Solwise, BroadbandBuyer, eBuyer, eBay, etc - just need to search around a bit).

The most advanced 4G router that I know of that is currently generally available in the UK is the more expensive Huawei B618 (https://www.amazon.co.uk/Unlocked-Router-Genuine-Warranty-network/dp/B073VBYFL5), which is an LTE Category 11 router. Still 2x2 MIMO though. There are 4x4 MIMO routers available - BUT all the ones I have seen thus far only have 2 antenna ports (SMA or TS-9) for external antennae, so if you need to use an external antenna, it turns the router into a 2x2 MIMO one anyway!

Some versions of the B525 (including mine, the B525s-65a) have Bridge Mode, and with mine you can even select the LTE band (either "Auto", "2G Only", "3G Only", "4G Only", "4G / 3G Auto", "4G (800MHz) only", "4G (1800MHz) only", "4G (2600MHz) only", "4G (700MHz) only" - in the case of my router). However, all these features are completely firmware dependant, and it's almost impossible to tell what features you will get until you get the router. However, even without the LTE band selection or bridge mode, the B525 is a good 4G router (from my own experiences, so far...).

I'm currently with Three (but Three-based Smarty are currently doing Unlimited Data for £18.75 per month on a rolling monthly (no contract) basis - see: https://smarty.co.uk/plans/unlimited).

Actually, all 4 main mobile operators (Three, Vodafone, EE & O2) now do unlimited data (although there are usually FUPs [Fair Usage Policies] that apply, O2's being the lowest at 650Gb per month, with Three [incl. Smarty] & EE having a 1Tb per month "soft cap", and Vodafone don't officially have any, although mention of an unofficial 3Tb per month "soft cap" for Vodafone has been made).

I'm thinking of adding a Vodafone unlimited data SIM to my setup, then load-balancing that with the Three link (via something like this: https://www.amazon.co.uk/TP-LINK-TL-R470T-Balance-Broadband-Business/dp/B004UC9V8Q), then combining the output of said Load Balancer with my slow (sub 2Mbps) ADSL link via my Draytek Vigor 2860Vac router - either as Load Balancing, or more likely to use the ADSL as Failover backup link.

Or you could use a "Yagi" style setup - but they are more directionally sensitive (I think, from what I've read) than the XPOL-A0002 (which, from testing a friends, almost acts as a hybrid directional & omni antenna!).

Now that all main mobile networks offer unlimited data (and the most expensive of these is £34 per month), 3G & 4G (using a dedicated router) does become a much better option to add into the mix for those of us still suffering with slow connections. As long as you have network coverage that is: use a PAYG test SIM with some credit on to test signals and run speed tests before choosing a network or committing to a contract. At least now that all 4 main operators offer unlimited(ish!) data, there are more options in terms of said coverage.

Hopefully this provides a bit of useful information to go on with.

In summary - yes, definitely look into getting a dedicated 4G router, possibly paired with an external (omni-directional or directional) antenna - it could massively boost your connection (and even save money, if you are bonding 4 ADSL lines - you could probably keep just the 1 or 2 "best" lines and combine with 4G via Load Balance [or FailOver to ADSL] if it works out).

Adam that’s just what I need. A fantastically generous post. Especially given that - due to illness - somehow I find it very difficult to locate products.

I would need to ask AA about the implications of using a non-dongle de ice for fallback. The usb dongle i/f may be special in that the Firebrick knows to switch over to the USB NIC when all the lines go down. I don’t know if there’s a way to get a different type of interface to be recognised by the Firebrick as a ‘failover solution’ - or whatever is the phrase I’m looking for. Without sorting that problem out, I could get downstream but not upstream to work.

I had been thinking about using the L2TP service with AA and a cheap SIM. It would not be cost effective for failover though, something that approximately never happens but I would have the recurring bills for L2TP and the mobile carrier. But if I were to start to go all-4G then that would make sense. What puts me off that is (i) droop - time-of-day related and no minimum performance guarantee as you’re depending on the popularity of the cell and how many hogs there might be; (ii) reliability - 4G disappears for a day or two sometimes and always fails when there is a local power outage, so it isn’t remotely reliable enough and would need DSL as backup.

About lightning and positioning: The ‘higher pole’ thing seems valid to me. However since it would cause a lightning strike if too prominent then there might still be damage to other systems nearby due to induction, no? gigantic magnetic and secondary electric fields around the place as the current flows down the pole plus the big problems of the dI/dt.

I wouldn’t mount an antenna high up, because it wouldn’t survive 130mph winds. I could get line of sight in a place where the house shields it from the prevailing wind, or given that the the hous is high up on a shelf above the road which is to the east and the basestation lies to the northeast across the valley, the bank below the house, the garden’s low stone wall and the house itself all shelter an antenna parked on that bank or in the garden. An antenna could be lower than the house and have a line of sight straight to the basestation. Indeed the satellite dish is at ground level, to the northeast of the house and is sheltered by the house itself.

I’ve never had a lightning strike on the house. The house has several 15m trees near to it and to the west of the house the land rises greatly as I am on the sloping side of Beinn nan Càrn, so I’m not the highest point. I think damage has been due to EPR/GPR or else induction in the phone lines. Neighbours slightly lower than me had a lightning injury inside housd though so it doesn’t do to be complacent.

Is it really important for an antenna to be outside? If I have it in the woman-cave former office bay window looking directly at the basestation, will that be enough?

I have a small antenna now; I keep asking Janet to help me plug it into the USB dongle - then I’ll know whether or not I’ve bought the right type of connector. :-(

I have now plugged in the antenna into the USB NIC. There is a tiny rubbery black cover on the side that can be peeled back to reveal a hole that takes a gold-plated push-in ‘hollow pin’ or tube-like concentric connector? I think this might be what is termed the ‘CRC9’ type of connector but I’m not sure, I’d have to look it up. The antenna itself has a slender lead going to it. My wife has parked the dongle plus antenna in the left hand pane of the bay window, which is facing north-east directly towards the basestation.

It has a screw-on suction-cup ‘foot’. This suggests sticking the foot onto the glass, but then it would be pointing 180 degrees away from the line of sight. Which direction should it be facing ? It will of course be an omni from the symmetrical look of it, but it will have a polar diagram of some sort surely, with respect to a plane in which its line of symmetry lies (‘latitude’ angle dimension/degree of freedom). I would think it has nulls or at least minima at the north and south poles, to a greater or lesser extent. Unless that is they have made it truly 4pi-symmetrical by having several orthogonally aligned elements whose outputs are combined, which I would very much doubt somehow. I get the feeling that the foot should be stuck onto a horizontal flat surface maybe, but who knows.

It seems to be working, from the evidence of the clueless.aa.net.uk control server. Later on when Janet has a few mins I will do a real speed test now, by forcing the Firebrick to switch over to 3G. I could fiddle about and try to trigger this forced switchover remotely, but I’d rather not have to kludge to the XML config.

The antenna is positioned at right-angles to the plane of the window, sucker cup attachment on the glass, so that means the main axis of the antenna is pointing directly away from the line of sight. Did a speed test; horrible results = 1.2 Mbps downstream / 0.2 Mbps upstream with https://speedtest2.aa.net.uk.

So a nightmare; either the antenna is horrible or the positioning is indeed a disaster.

When I was messing around with the Huawei router I found it very very sensitive to exact antenna orientation. Based my experience then, you really want a live read out of RSRP while trying different locations or orientation. Is this still with your 3G dongle, if so then of course it'll be a 3G parameter to be monitored.

Janet has re-oriented the antenna to have its axis of symmetry vertical, sucker cup is on a horizontal surface, and I need to do another speed test to compare the signal strength indirectly. I don’t have a way of getting the actual signal strength readings out of it.